Anti-skid mechanism

ABSTRACT

An anti-lock device for a vehicle brake system is provided with a control valve actuated in response to signals from a sensing mechanism to subject a control member to vacuum and selectively subject said control member to atmosphere for controlling the application of supplied fluid pressure to a vehicle brake, and throttling valve means is provided to control the subjection of said control member to the vacuum.

Unite States Patent 1191 Machek Jan. 22, 1974 ANTI-SKID MECHANISM 3,162,092 12/1964 Corwin 91/26 3,295,547 1/1967 Scaramucci 137/512.l5 X [75] Machek Creve Com", 3,610,273 10/1971 Russell 137/5139 73 Assignee; Wagner Electric Corporation, 3,613,733 10/1971 Machek 251/282 X Newark, FOREIGN PATENTS OR APPLICATIONS [22] Filed: Dec. 13, 1972 610,945 10/1948 Great Britain 91/26 14 [21] Appl No 3 ,820 Primary Examiner-1rwin C. Cohen Related US. Applica ion Data Attorney, Agent, or FirmJames R. Bell [62] Division of Ser. No. 199,431, Nov. 17, 1971, Pat. No.

3,752,536 1571 ABSTRACT 52 us. (:1 91/26, 137/512.15, 137/5133 anti-lock device for a vehicle brake System is [51] Int CL H F151, 11/03, 1215b 13/04 F15b 15/22 vided with a control valve actuated in response to sig- 3 Field of Search 91/24 25, 137/5115, nals from a sensingwmechanism to subject a control 137/5123, 5133 member to vacuum and selectively subject said control member to atmosphere for controlling the appli- 5 References Cited cation of supplied fluid pressure to a vehicle brake, UNITED STATES PATENTS and throttling valve means is provided to control the subjection of said control member to the'vacuum. 1,833,216 11/1931 Hanna 91/25 2,699,844 1/1955 McIntyre 137/5133 X 3 Claims, 6 Drawing Figures as 89 7 53 60 79 54 52 g 45 ANTI-SKID MECHANISM This application is a division of my copending United States application Ser. No. 199,431 filed Nov. 17, 1971, now U.S. Pat. No. 3,752,536.

FIELD OF THE INVENTION This invention relates generally to brake systems and in particular to anti-lock devices for use therein.

BACKGROUND OF THE INVENTION In the past anti-lock brake systems for vehicles, antilock devices were provided with a control member which was normally vacuum immersed having one side thereof selectively subjected to atmosphere to establish a driving differential force across said control member and effect the predetermined movement thereof toward a position interrupting fluid pressure communication between a vehicle master cylinder and a brake device and relieving the intensity of the fluid pressure applied to said brake device upon the occurrence of impending vehicle skid conditions. The impending vehicle skid condition was sensed by a sensor device which looked at the deceleration of a vehicle wheel during a braking application, and through an electronic logic device, a signal denoting such impending vehicle skid condition was sent to the anti-lock device to effect actuation thereof and relieve the fluid pressure applied from the master cylinder to the vehicle brake. One of the main undesirable or disadvantageous features of such past anti-lock devices is that they created an undesirably long time delay between the sensing of the impending vehicle skid condition and the actuation of said anti-lock device to relieve the fluid pressure applied to the vehicle brake. Another disadvantageous or undesirable feature of such past anti-lock devices was that the time necessary for them to breathe, i.e., exhaust the atmosphere from the control member to deactuate the anti-lock device, was inordinately long thereby adding to the aforementioned time delay. And yet another disadvantageous or undesirable feature of such past anti-lock devices was their tendency upon deactuation to overshoot the pressure at which the impending skid condition was sensed thereby effecting a subsequent application of fluid pressure to the vehicle brake which might further effect a vehicle skid.

The principle object of the present invention is to provide an anti-lock device which overcomes the aforementioned undesirable or disadvantageous features of the past anti-lock device, and this, as well as other objects, features and advantages of the present invention will be understood from the following description and associated drawings.

SUMMARY OF THE INVENTION Briefly, the present invention includes an anti-lock device having control means selectively subjected to a differential air-vacuum pressure for controlling the application through said anti-lock device of fluid pressure supplied thereto, and a balanced control valve is actuated by a solenoid to control the selective subjection of said control means to the differential airvacuum pressure. Another aspect of the present invention includes throttling valve means for snubbing or throttling the evacuation of atmosphere pressure applied to the control means upon the de-actuation of the anti-lock device.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings, which illustrate an embodiment of the invention and wherein like numerals refer to like parts wherever they occur:

FIG. 1 is a partial sectional view illustrating a preferred embodiment of the present invention partially in cross-section;

FIG. 2 is a sectional view taken along line "2-2" of FIG. 11;

FIG. 3 is a fragmentary sectional view taken along line "33" in FIG. 2;

FIG. 4 is a fragmentary view taken along line "44 in FIG. 3 illustrating a plan elevation of the throttling valve used in the preferred embodiment of the present invention;

FIG. 5 is a fragmentary sectional view illustrating an alternate construction of a throttling device for use in the present invention in cross-section; and

FIG. 6 is a fragmentary view taken along line "6-6 in FIG. 5 illustrating a plan elevation of the alternate throttling device.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings in detail and in particular to FIG. 1, an anti-skid or anti-lock device, indicated generally at l, is provided with a power housing or portion 2 having opposed, generally disc or cup shaped cylinder or housing members 3, 4, and said housing members are provided with opposed peripheral edge portions 5, 6 and opposed base walls 7, 8, respectively. The cylinder members 3, 4 are releasably secured adjacent to their respective opposed peripheral edges 5, 6 by clamping means, such as a plurality of nut and bolt assemblies 9, and an annular diaphragm member 10 is compressed in sealing engagement between said opposed peripheral edges dividing the power housing 2 into opposed vacuum and differential air-vacuum chambers 11, 12 which are respectively defined between the opposed sides of said diaphragm and the base walls 7, 8 of the cylinders 3, 4. The diaphragm 10 is provided with a centrally located aperture 13 which is retained in sealing or clamped engagement between the peripheral surface 14 of a sleeve or driving member 15 and an annular spring retainer 16 fixedly positioned on said driving member peripheral surface by suitable means, such as staking as shown at 17. A pair of concentric springs 18, 19 are respectively pre-compressed between the retainer 16 and the cylinder base wall 7 urging said retainer, the diaphragm 10 and the driving member 15 rightwardly toward the cylinder base wall 8, and a centrally located aperture 20 is provided through said cylinder base wall 8.

The driving member 15 is provided with an axial blind bore 21 extending through the rightward end thereof substantially coaxial with the cylinder aperture 20, and a resilient bumper 22 is retained on the leftward or closed end of said driving member for engagement with the cylinder base wall 7 to limit the reciprocating axial movement of said driving member, as discussed hereinafter. A guide member 23 is provided with integral sleeve and radially extending flange portions 24, 25, and a bore 26 extends axially through said guide member. The sleeve portion 24 of the guide member 23 extends coaxially through the cylinder aperture 20 into sliding and guiding engagement with the blind bore 21 of the driving member 15, and the flange 25 is abutted in displacement preventing engagement between a control housing 27 and the exterior side of the cylinder base wall 8 about said cylinder aperture therein, said control housing being connected with said cylinder base wall by suitable means, such as a plurality of screws 28.

Referring now to FIGS. 1 and 2, the control housing 27 is provided with a bore 29 axially interposed between counterbores or outlet and inlet chambers 30, 31 and substantially coaxial with the cylinder aperture 20, and opposed annular shoulders 32, 33 are provided on said control housing at the intersections of said bore and counterbores, respectively, said shoulder 33 defining a valve seat. The rightward end of the counterbore 31 defines an inlet port for connection in pressure fluid communication with a fluid pressure generating means, such as a master cylinder or pump or the like (not shown and an outlet port 35 is provided in the control housing 27 intersecting with the counterbore adjacent to the shoulder 32, said outlet port being adapted for connection in pressure fluid communication with a vehicle brake (not shown). A valve spring 37 is biased between an abutment, such as the hose nipple 37, in the counterbore 31 and a valve member 38 urging said valve member toward engagement with the valve seat 33, and an integral extension 39 is provided on said valve member protruding coaxially through the bore 29 and having a free end portion 40 for abutting engagement with a driven member, such as the control piston 41, in the counterbore 30. The control piston 41 is slidably and guidably received in the bore 26 of the guide member 23 and extends coaxially into the control housing counterbore 30 through an annular sealing member 42 positioned in seating engagement with the guide member flange 25 and in sealing engagement between said control piston and the control housing 27. The sealing engagement of the seal 42 with the control piston 41 defines an effective area A, on said control piston which is subjected to the applied fluid pressure at the outlet port at all times. Opposed ends 43, 44 are provided on the control piston 41,-and the force of the springs 18, 19 acting through the driven member and retainer 15, 16 normally drivingly urges said driven member into abutting engagement with the end 43 of said control piston whereby the other control piston end 44 is normally urged toward engagement with the control housing shoulder 32 and valve member free end to displace the valve member 38 from its cooperating valve seat 33 thereby normally effecting open pressure fluid communication between the inlet and outlet ports 34, 35.

Referring now also to FIG. 3, the control housing 27 is also provided with another bore or delivery chamber 45 interposed between opposed counterbores 46, 47 which respectively defines vacuum and atmospheric chambers, and opposed shoulders 48, 49, which define valve seats, are provided on said control housing at the intersections of said bore with said counterbores, respectively. An arcuate recess 50 is provided in the control housing 27 interconnected between the counterbore 46 and intersecting vacuum and connecting ports 51, 52 in said control housing. The vacuum port 51 is adapted for connection with a vehicle vacuum source (not shown), and a connecting conduit 53 has one end sealably received in the connecting port 52 by suitable means, such as the resilient grommet 54, while the other end thereof is sealably received by suitable means, such as another resilient grommet 55, which is positioned in an aperture 56 provided in the cylinder 3 of the power housing 2; therefore, the power housing vacuum chamber 11 is connected through the connecting port and conduit 52, 53 with the vacuum port 51. An annular valve diaphragm receiving recess 57 is provided in the lower end of the control housing 27 about the counterbore 47, and an air or atmospheric port 58 is provided in said control housing intersecting with said counterbore.

A dumbbell type control valve, indicated generally at 59, is provided with a stem portion 60 which extends. substantially coaxially through the bore 45 having opposed valve members 61, 62 thereon in the counterbore 46, 47 for sealing engagement with the valve seats 48, 49, and such sealing engagement between said valve members and seats defining effective areas A A;,, respectively, as discussed hereinafter. The lower valve member 62 is provided with an upper sealing portion or head 63 which is integrally formed with an annular diaphragm or working portion 64 and a lower annular retainer or sealing portion 65. The retainer portion 65 is disposed in the housing recess 57 in sealing and displacement preventing engagement between the control housing 27 and a retainer or housing closure member 66 which is connected with said housing closing the counterbore 47 by suitable means, such as a plurality of screws 67, and it should be noted that an effective area A, is defined at the intersection or flexing locus of said diaphragm and retainer portions which is substantially equal to the area A The head portion 63 is received in displacement preventing engagement in a peripheral groove 68 of a valve sleeve or insert 69 having axial passage means 70 therethrough and threadedly connected for concerted movement with the lower end of the stem 60. The negligible compressive force of a valve spring 71 biased between the insert 70 and the retainer 66 urges the head portion 63 of the valve 62 into sealing engagement with valve seat 49 thereby isolating the atmospheric chamber 47 which is in communication with the atmospheric port 58 at all times. It should be noted that the valve member 62 defines with the retainer 66 a valve chamber 73 which is within the atmospheric chamber 49 and selectively subjected to either atmosphere or vacuum prevailing in the delivery chamber 45 through the passage means 70 of the valve insert 69 which is connected in communication with the delivery chamber 45 at all times; therefore, since the areas A;,, A are substantially equal and the valve chamber 73 is subjected to either vacuum or atmosphere prevailing in the delivery chamber 45, then it is apparent that the valve 62 is predeterminately balanced.

An electric solenoid assembly 74 of a type well known in the art is removably secured to the control housing 27 by suitable means, such as a plurality of screws 75, closing the upper end of the control housing counterbore 46, and sealing means 76 is sealably interposed between said control housing and solenoid assembly about the upper end of said counterbore 46. The solenoid 74 is provided with magnetizable pole piece 77 and a shiftable armature member 78 which is drivingly engaged with the upper end of the valve stem 60, said armature member being shiftable to actuate the valve 59 upon energization of said solenoid and magnetization of said pole piece in response to electrical signals of an impending skid condition transmitted to said solenoid from a vehicle wheel speed sensing mechanism and an electrical logic circuit therefor (not shown) as is well known in the art.

Referring now to FIGS. 3 and 4, the control housing 27 is also provided with a connecting passage means or a stepped bore 79 having one end intersecting with the bore 45 adjacent to its mid-portion and the other end thereof connected with the power housing chamber 12 through a large aperture 80 and a plurality of smaller apertures or ports 81 adjacent thereto respectively provided in the base wall 8 of the cylinder 4, and a plurality of valve seats 81a are provided on said base wall about said smaller apertures. A throttling device .or mechanism, indicated generally at 82, is provided with ,a mounting or body portion 83 having an annular groove 84 therein which is received in the cylinder larger aperture 80 in sealing and displacement preventing engagement with the cylinder base wall 8, and a bore or aperture 85 is provided through said throttling mechanism body. A cup or thimble shaped throttling valve element or member 86 having passage means 87 therethrough is slidably and sealably received in the body bore 85, and a valve seat 88 is provided on one end of said throttling valve element about said passage means therethrough for sealing engagement with the diaphragm 10 in the power housing chamber 12. The throttling valve element 86 is also provided with a radially extending flange 89 on the other end thereof within the control housing stepped bores 79 for abutting or displacement preventing engagement with the body 83 about the bore 85 therethrough to predeterminately limit the movement of said throttling valve element with the diaphragm 10, as discussed hereinafter, and the negligible force of a valve spring 90 biased between the control housing 27 and the throttling valve element 86 normally urges the valve seat 88 and the flange 89 toward engagement with the power diaphragm 10 and the body 83. The throttling valve body 83 is also provided with a plurality of integrally formed flapper valves or unidirectional check valves 91 which extend into sealing engagement with the valve seats 81a, and an exhaust throttling passage or restricted reverse flow aperture, such as the orifice 92, is provided in each of said flapper valves to effect restricted communication or flow in the exhausting direction from the chamber 12 to the control housing stepped bores 79.

OPERATION In the operation and assuming, of course, that the vehicle is operative to establish vacuum at the vacuum port 51, the component parts of the anti-lock device 1 are in their normal or inoperative positions, as shown in the drawings and as described hereinbefore; therefore, the power housing chamber 11 is evacuated through the power housing aperture 56, the connecting conduit 53, the control housing aperture 56, the conn ecting conduit 53, the control housing connecting port 52, and said vacuum port, and the power housing chamber 12 is also evacuated through the restricted passages 92 of the throttling mechanism 82, the control housing passage means 79, the bore 45, the counterbore 46, the recess 50 and said vacuum port. With the power housing chambers l l, 12 so evacuated, the compressive forces Fs of the power springs 18, 19 urge the diaphragm 1 0, retainer 16, and driving member rightwardly in the power housing 2 toward a normal position to drivingly engage said driving member with the control piston end 43 and concertedly urge the control piston 41 rightwardly to abut the rightward end 44 thereof with the control housing shoulder 32 and the free end of the check valve extension 39 thereby displacing the check valve 38 against its spring 36 from its cooperating valve seat 33 to establish open pressure fluid communication between the inlet and outlet ports 34, 35. In this manner. supplied or input fluid pressure from the master cylinder (not shown) flows from the inlet port 34 through the control housing bore 29 and counterbores 30, 31 to the outlet port 35 being applied therefrom to actuate a vehicle brake wheel cylinder and energize a vehicle brake (not shown), and the applied or output fluid pressure at said outlet port acts on the effective area A, of the control piston 41 to establish a force F, acting in opposition to the compressive forces of the power springs 18, 19.

When the vehicle brake is so energized, the rate of the vehicle velocity is, of course, decreased, and a sensing device and an electronic circiut (not shown) is utilized to measure the decreasing rate of velocity and ascertain the critical rate thereof denoting impending vehicle skid conditions, such as in the event the applied fluid pressure is great enough to lock up" the vehicle brake. When the sensing device ascertains such impending vehicle skid condition, a signal is transmitted by the electronic circuit to the solenoid 74 which is then electrically energized to move the control valve 59 downwardly against the negligible force of the spring 71 toward an operative or actuated position engaging the valve member 61 with its valve seat 48 and disengaging the head portion 63 of the valve member 62 from its cooperating valve seat 49. Of course, the engagement of the valve member 61 with the valve seat 48 isolates the bore 45 from the vacuum port 51, and the disengagement of the valve member 62 from the valve seat 49 effects the application or flow of atmospheric air from the atmospheric port 48 through the atmospheric chamber 47 into the valve chamber 73 and the housing bore 49 and passage means 79. The applied atmospheric air initially flows from the passage means 79 through the apertures 81 in the cylinder wall 8 into the power housing chamber 12 displacing the check valves 91 from engagement with their valve seat 81a. The application of atmospheric air in the power housing chamber 12 and the prevailing vacuum in the power housing chamber 11 establishes a differential air-vacuum force F acting across the diaphragm 10 in a direction assisting the force F, acting on the control piston 41 and in opposition to the power spring force Fs. When the forces F F attain a value great enough to overcome the power spring force Fs, the diaphragm 10 and control piston 41 are concertedly moved very rapidly in a leftward direction toward an operative position initially disengaging the control piston end 40 from the check valve 38, and the check valve spring 36 urges said check valve into sealing engagement with the valve seat 33 interrupting pressure fluid communication between the inlet and outlet ports 34, 35. Upon the interruption of pressure fluid communication between the inlet and outlet ports 34, 35, further leftward movement of the control piston 41 effects volumetric expansion of the control housing outlet chamber 30 reducing the magnitude of the applied fluid pressure at the outlet port 35 which, of course, serves to reduce the intensity of the vehicle brake energization and the vehicle deceleration rate thereby obviating the impending skid condition.

Upon the very rapid, concerted, leftward movement of the diaphragm 10 and control piston 41 in response to the forces F F acting against the spring force Fs, the negligible force of the spring 90 concertedly moves the throttling valve member 86 with said diaphragm through a predetermined distance until the flange 89 of said throttling valve member becomes abutted with the throttling member body 83 about the bore 85 therethrough, and thereafter further leftward movement of said diaphragm effects the disengagement thereof from the valve seat 88 on said throttling valve member to open the passage means 87 and permit applied and exhausting passage of atmospheric air therethrough between the control housing passage means. 79 and the power housing chamber 12. It should be noted that the passage of the applied atmospheric air through the housing apertures 81 is substantially unrestricted to insure rapid translatory movement of the diaphragm l and control piston 41 in the leftward direction in order to very quickly alleviate or reduce the applied fluid pressure at the outlet port 35 to obviate the impending skid condition. Of course, the concerted leftward movement of the diaphragm l0 and control piston 41 is ultimately limited by the engagement of the driven member bumper 22 with the rear or end wall 7 of the power housing 2.

The aforementioned increase in the rate of vehicle velocity in response to the reduction of the applied fluid pressure is, of course, sensed by the sensing means which ascertains that the danger of a vehicle skid is now past, and another signal is now transmitted by the electronic circuit to the solenoid 74 which effects deenergization thereof. Upon the de-energization of the solenoid 74, the force of the air-vacuum differential acting across the area A of the valve member 61 assisted by the valve return spring 71 urges the control valve 59 upwardly toward its normal position reengaging the valve member 62 with its valve seat 49 and again disengaging the valve member 61 from its valve seat 48 to selectively interrupt pressure fluid communication between the atmospheric port 58 and the power housing chamber 12 and selectively reestablish communication between said power housing chamber and the vacuum port 51. Upon the re-establishment of communication between/ the vacuum port 51 and power housing chamber 12, the atmospheric air is initially exhausted from said power housing chamber passing through the passage 87 in the throttling valve member 86, the control housing stepped passage 79, the bore 45, the counterbore 46, and the recess 50 to the vacuum port 51, and in this manner, the differential force F acting across the diaphragm 10 is correspondingly reduced. Upon the initial reduction of the differential force F the opposing power spring force Fs effects an initial, very rapid, concerted movement of the diaphragm l0 and control piston 41 rightwardly toward their original positions until said diaphragm re-engages the valve seat 88 on the throttling valve member 86 to again close the passage means 87 therethrough. When the throttling valve member passage means 87 is closed, the differential of the partially exhausted atmospheric air in the power housing chamber 12 as compared with the vacuum being created in the control cylinder passage 79 acts across the flapper valves 91 of the throttling mechanism body 83 urging them toward sealing engagement with their valve seats 81a. Thereafter, further evacuation or exhausting flow of the atmospheric air from the power housing chamber 12 is effected only through the restricted orifices 92 in the flapper valves 91 which dampens or reduces the speed of the terminal portion of the concerted rightward movement of the diaphragm 10 and control piston 41 toward their original positions. Of course, when all of the atmospheric air is so evacuated from the power housing chamber 12, the difi'erential force F is eliminated and the power spring force Fs then concertedly drives the diaphragm 10, the control piston and the throttling member 86 to their original positions reengaging the control piston end 44 with the housing shoulder 32 and the check valve 38 to effect the dis placement thereof against its spring 36 from its valve seat 33 and re-establish pressure fluid communication between the inlet and outlet ports 34, 35. Of course, the initial, very rapid, rightward movement of the control piston 41 in the control housing counterbore 30 effects a very rapid re-establishment of the magnitude of the applied fluid pressure at the outlet port 35 to approximately that magnitude when an impending skid condition was originally sensed to again increase the intensity of the vehicle brake energization resulting in a corresponding vehicle velocity rate decrease to again cause the sensing device to signal for the energization of the solenoid 74. Of course, the terminal portion of the translatory rightward movement of the diaphragm 10 and control piston 41 is snubbed or damped, as mentioned hereinbefore, in order to maintain the vehicle deceleration substantially constant at a higher rate for a longer period of time which prevents overshooting of the pressure at which the original impending skid condition was sensed upon the subsequent reestablishment of the pressure at the outlet port 35 to re-energize the vehicle brakes.

It should be noted that the magnetic or operating characteristics of solenoids, such as the solenoid 74, require an extremely high exciting current to energize the armature 78 and effect initial actuation thereof, as compared for instance with the current necessary to maintain said armature in its energized position in magnetic holding engagement (not shown) with its pole piece 77. In other words, once the armature 78 is mag.- netically urged downwardly or toward engagement with the pole piece 77, the current necessary to maintain such magnetic holding engagement is appreciably less than that needed to excite or initiate the movement of said armature toward said pole piece, and this characteristic is, in the most part, due to the air gap between said armature and pole piece. Therefore, since the exciting current is extremely high, it is desirable to balance the forces acting across the control valve 59 in its original position, as shown, so that the exciting current acting on armature 78 to effect the initial actuation thereof toward magnetic holding engagement with the pole piece 77 is opposed only by the negligible force of the valve return spring 71. In the normal operating position of the control valve 59, it should be noted that the valve chamber 73 is exhausted through the valve passage means to the control housing bore 45; therefore, since the opposing areas A A, are substantially equal and subjected to vacuum in said control housing bore and said valve chamber, it is apparent that any forces acting on the valve member 62 are equal and opposite, thereby self-cancelling, wherein said valve member 62 and the control valve 59 are balanced in the normal operating positions thereof. Of course, with the control valve 59 so balanced in its original or normal operating position, it is apparent that smaller electrical coils (not shown) can be employed in the solenoid 74 to actuate the armature 78 and the control valve 59 since the forces opposing the solenoid exciting current are predeterminately minimized.

When the solenoid 74 is energized as previously discussed, the armature 78 is moved downwardly toward magnetic holding engagement with the pole piece 77 to actuate the control valve 59 to its operative position against only the neglibible force of its return spring 71 thereby engaging the valve member 51 with its seat 48 to isolate the control housing bore from vacuum and disengaging the valve member 62 from its seat to subject said control housing bore to atmosphere. With the control valve 59 in its operating position, the valve chamber 73 is subjected through the valve passage 70 to the prevailing atmosphere in the control housing bore 45, and since the areas A A are equal, as previously mentioned, the forces acting across the valve member 62 are also balanced in the open or operative position thereof. Of course, the atmosphere and vacuum prevailing in the control housing bore and counterbore 45, 46 respectively acting on area A of the valve member 61 when it is engaged with the valve seat 48 establishes a differential force acting against the force of the magnetic holding engagement of the armature 78 with the pole piece 77; however, as previously mentioned, the current necessary to maintain the mag netic holding engagement between said armature and pole piece is appreciably less than that necessary to excite said armature toward such magnetic holding engagement with said pole piece.

Referring now to FIGS. and 6, an alternative construction of a throttling device, indicated generally at 100, is shown for use in the anti-lock device 1 having substantially the same component parts and functioning in substantially the same manner as the previously described throttling device 82 with the following exceptions.

The housing 27 is provided with a connecting passage means or stepped bore 101 having one end intersecting with the bore 45 adjacent to its mid-portion and the other end thereof connected with the power housing chamber 12 thorugh an aperture 102 provided in the base wall 8 of the cylinder 4. The throttling device or mechanism 100 is provided with a mounting portion or grommet 103 having an annular peripheral groove 104 therein which is received in the aperture 102 in sealing and displacement preventing engagement with the cylinder base wall 8, and a bore or aperture 105 is provided through said grommet. A throttling valve element or member, such as the stepped piston 106, is slidably received in the grommet bore 105 having a reduced portion or extension 107 extending into the power housing chamber 12 and defining with said piston a shoulder 108 thereon. A stepped bore or passage 109 is provided through the throttling valve member 106, and a valve seat 110 is provided on the extension 107 about said passage 109 for sealing engagement with the diaphragm in the power housing chamber 12, said valve seat being urged into sealing engagement with said diaphragm by the negligible force of a valve return spring 1 1 l engaged between said throttling valve member and the housing 27. The throttling valve member 106 is also provided with a plurality of aperture or passages 112 extending through the shoulder 108 between the throttling valve member stepped bore 109 and the power housing chamber 12, and a flapper valve or unidirectional valve means 113 is provided to permit the passage of atmosphere through said apertures 112 only in the direction from said throttling valve bore into said power housing chamber. The uni-directional check valve 113 is provided with an axially extending collar portion 114 which is received in displacement preventing engagment on the periphery of the throttling valve extension 107, and an annular flapper or valve portion 115 is integrally formed with said collar 114 extending radially therefrom into sealing engagement with a plurality or valve seats 116 defined on the shoulder 108 about the aperture 112 therethrough. A plurality of exhausting throttling passages or restricted reverse flow passages, such as the orifices 1 17, are provided through the flapper valve 115 in alignment with the apertures 1 12 to effect only restricted communication or exhausting atmospheric air flow therethrough in the exhausting direction from the power housing chamber 12 to the throttling valve stepped bore 109. To complete the description of the throttling device 100, the throttling valve member 106 is also provided with a radially extending flange 118 within the control housing stepped bore 101 for abutting or displacement preventing engagement with the grommet 103 to predeterminately limit the movement of said throttling valve member with the diaphragm 10 in excess of a predetermined amount.

Upon the energization of the solenoid 74 in response to preselected conditions to actuate the control valve 59 and effect the passage of atmosphere into the delivery chamber 45, as previously discussed, the atmosphere flows therefrom through the housing passage 101 and the throttling valve bore 109 and apertures 112 into the power housing chamber 12 displacing the uni-directional valve means 113 from its cooperating valve seats 116. The establishment of atmospheric air in the power housing chamber 12 and the prevailing vacuum in the power housing chamber 11 creates the differential air-vacuum force F across the diaphragm 10 to effect the movement thereof toward its operative position assisted by the force F against the spring force Fs, and the valve spring 111 urges the throttling valve member 106 in concerted movement with said diaphragm through the predetermined amount until the flange 118 abuttingly engages the grommet 103 thereby containing said valve spring. Upon the engagement of the flange 118 with the grommet 103, further movement of the diaphragm 10 in response to the differential force F effects the disengagement of said diaphragm from the valve seat of said throttling valve member opening the bore 109 thereof to permit the ingress and egress of the atmospheric air therethrough to and from the power housing chamber 12.

Upon the subsequent de-energization of the solenoid 74 in response to preselected conditions to de-actuate the control valve 59 and effect the exhaustion of the applied atmospheric air from the power housing chamber 12, as previously discussed, the exhausting atmosphere, of course, urges the uni-directional valve means 113 into engagement with its valve seats 116 and initially flows from said power housing chamber through the throttling valve member bore 109, the control housing bore 101, and the delivery and vacuum chambers 79, 46 of the control housing 27. This evacuation of the atmospheric air from the power housing chamber effects a corresponding reduction of the differential force F acting across the diaphragm wherein the spring force Fs thereafter very rapidly moves said diaphragm toward its original position and into reengagement with the valve seat 110 of the throttling valve member 106. Upon the re-engagement of the diaphragm 10 with the throttling member valve seat 110, the throttling member bore 109 is closed interrupting pressure fluid communication therethrough between the power housing chamber 12 and the control housing stepped passage 101 which, in effect, damps or snubs the movement of said diaphragm toward its original position in response to the spring force Fs; however, such damped movement of said diaphragm is thereafter controllably effected by the exhausting passage of the remaining atmospheric air from said power housing chamber through the restricted orifices 117 and throttling member apertures 105 to said throttling member bore. When the exhausting passage of the atmospheric air from the power housing chamber 12 is completed, the differential force F is eliminated, and the spring force Fs urges the diaphragm 10 and component parts connected therewith to their original positions as previously described and as shown in the drawings. In this manner, it is obvious that the atmospheric air is quickly applied to the power housing chamber 12 through the throttling member apertures 105 to effect a very rapid movement of the diaphragm 10 against the springs 18, 19 toward its operative position permitting the control piston 41 to very rapidly relieve the applied fluid pressure at the brakes (not shown), and the exhausting flow of atmospheric air from said power housing chamber is quickly accomplished through the throttling member bore 109 to effect an initial very rapid return movement of said diaphragm toward its original position to drive said control piston thereby very rapidly reestablishing the applied fluid pressure at said brakes; however, the terminal portion of such return movement is snubbed or damped by the engagement of said diaphragm with the throttling member valve seat 110 and the subsequent exhaustion of atmospheric air 7 through the orifices 117 in order to maintain the vehicle deceleration substantially constant at a higher rate for a longer period of time which prevents overshooting of the pressure at which the original impending skid condition was sensed upon the subsequent reestablishment of the applied fluid pressure to reenergize the vehicle brakes.

From the foregoing, it is now apparent that a novel anti-lock device 1, as well as a novel control valve 27 and novel throttling devices 82, 100 therefor, meeting the objects and advantageous features set forth hereinbefore, as well as others, is provided and that changes as to the precise configurations, shapes and details of the construction set forth in the disclosure by way of illustration may be made by those skilled in the art without departing from the spirit of the invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a housing having a fluid pressure responsive member therein defining therewith an expansible chamber, said member movable in said housing between opposed positions in response to fluid pressure selectively applied thereto and exhausted therefrom,

and resilient means to urge said member to one of its opposed positions, the improvement comprising:

a throttling device for controlling the passage therethrough of fluid pressure selectively applied to and exhausted from the expansible chamber in said housing, said throttling device including:

uni-directional valve means including a movable member for effecting the passage only of applied fluid pressure into said chamber to initiate the movement of said pressure responsive member from one of its opposed positions toward the other thereof;

second valve means engaged with said pressure responsive member in one of the members opposed positions and disengaged from said member upon the movement thereof in excess of a predetermined amount toward the other opposed position of the member, said second valve means including passage means for effecting the passage of applied and exhausted fluid pressure to and from said chamber when said second valve means is disengaged from saidmember, said second valve means interrupting the passage therethrough of both the applied and exhausted fluid pressure when engaged with said pressure responsive means in its one opposed position;

orifice means included in said movable member of said uni-directional valve means for restricting the passage therethrough of exhausted fluid pressure from said chamber when said second valve means is engaged with said pressure responsive member;

a valve seat on said secon d va lve means about said passage means for engagement with said pressure responsive member, said valve seat being engaged with said member in its one opposed position to preclude the passage of fluid pressure through said passage means and being disengaged from said member upon the movement thereof in excess of the predetermined amount toward its other opposed position to effect the passage of applied and exhausted fluid pressure to and from said chamber through said passage means; and

a resilient mounting portion mounted in said housing,

said movable member of said uni-directional valve means being integrally formed with said mounting portion, and said second valve means being movable in said mounting portion.

2. A housing according to claim 1 e'fifiii's'ing aper ture means in said housing, valve seat means on said housing about said aperture means and within said chamber for engagement with said movable member of said uni-directional valve means, said movable member of said uni-directional valve means being movable toward a position disengaged from said valve seat means in response to only applied fluid pressure acting thereon to open said aperture means and permit the passage therethrough of the applied fluid pressure only into said chamber and being urged toward engagement with said valve seat means on said housing to close said aperture means upon the exhaustion of fluid pressure from said chamber.

3. A housing according to claim 1, comprising an aperture in said housing connecting with said chamber, said resilient mounting portion including mounting means sealably engaged with said housing about said aperture and defining a bore through said mounting 3,786,722 13 14 portion connecting with said chamber, said second only the passage of applied fluid pressure through said valve means being movable in said bore, aperture means in said housing adjacent to said housing aperv v ture, said movable member of said unirdirectional valve means bemg ahgred wlth sald aperture means means being disposed within said chamber to permit aperture means into said chamber, and said orifice UNITED STATES PATENT OFFICE- CERTIFICATE OF CORRECTION Patent No. 3,73 ,722 u Dated Jenuar 22, 1974 Inventor(s) "John A. Machek It is certified that error eppears in the above-identified patent and that said Letters Patent are'hereby'corrected as shown below:

Column 3, line 23 "37" should read 36 Column 5, line 57; after '53? delete down to and including "53 in line 58.- Column 6, line 39, "48" should read r 58 Column 9, line 14, "51 should sighed and sealed this 16th day of July 1974.

(SEAL) Attest: I ,v

MCCOY M. GIBSON, JR. c. MARSHAL'L DANN Attesting 0fficer Commissioner of Patents I FOIRM P0-105O (10-69) v Q uscoMM-Dc 60376-P69 Y [1.5. GOVERNMENT PRINTING OFFICE I919 0-366-384, 

1. In a housing having a fluid pressure responsive member therein defining therewith an expansible chamber, said member movable in said housing between opposed positions in response to fluid pressure selectively applied thereto and exhausted therefrom, and resilient means to urge said member to one of its opposed positions, the improvement comprising: a throttling device for controlling the passage therethrough of fluid pressure selectively applied to and exhausted from the expansible chamber in said housing, said throttling device including: uni-directional valve means including a movable member for effecting the passage only of applied fluid pressure into said chamber to initiate the movement of said pressure responsive member from one of its opposed positions toward the other thereof; second valve means engaged with said pressure responsive member in one of the members opposed positions and disengaged from said member upon the movement thereof in excess of a predetermined amount toward the other opposed position of the meMber, said second valve means including passage means for effecting the passage of applied and exhausted fluid pressure to and from said chamber when said second valve means is disengaged from said member, said second valve means interrupting the passage therethrough of both the applied and exhausted fluid pressure when engaged with said pressure responsive means in its one opposed position; orifice means included in said movable member of said unidirectional valve means for restricting the passage therethrough of exhausted fluid pressure from said chamber when said second valve means is engaged with said pressure responsive member; a valve seat on said second valve means about said passage means for engagement with said pressure responsive member, said valve seat being engaged with said member in its one opposed position to preclude the passage of fluid pressure through said passage means and being disengaged from said member upon the movement thereof in excess of the predetermined amount toward its other opposed position to effect the passage of applied and exhausted fluid pressure to and from said chamber through said passage means; and a resilient mounting portion mounted in said housing, said movable member of said uni-directional valve means being integrally formed with said mounting portion, and said second valve means being movable in said mounting portion.
 2. A housing according to claim 1, comprising aperture means in said housing, valve seat means on said housing about said aperture means and within said chamber for engagement with said movable member of said uni-directional valve means, said movable member of said uni-directional valve means being movable toward a position disengaged from said valve seat means in response to only applied fluid pressure acting thereon to open said aperture means and permit the passage therethrough of the applied fluid pressure only into said chamber and being urged toward engagement with said valve seat means on said housing to close said aperture means upon the exhaustion of fluid pressure from said chamber.
 3. A housing according to claim 1, comprising an aperture in said housing connecting with said chamber, said resilient mounting portion including mounting means sealably engaged with said housing about said aperture and defining a bore through said mounting portion connecting with said chamber, said second valve means being movable in said bore, aperture means in said housing adjacent to said housing aperture, said movable member of said uni-directional valve means being disposed within said chamber to permit only the passage of applied fluid pressure through said aperture means into said chamber, and said orifice means being aligned with said aperture means. 